The contractor shall continue to evaluate the efficacy of partially purified human leukocyte interferon (prepared by Cantell in Finland and processed and packaged by RIT in Belgium) in patients with varicella-zoster infections. These studies will be done on patients who are immunosuppressed by a concommitant malignancy or who have congenital immune deficiencies. In addition, the contractor will evaluate interferon levels, serum, brain tissue extracts and cerebral spinal fluid of patients with rabies which will be obtained throught the Center for Disease Control.